< draft-ietf-httpbis-proxy-status-03.txt		draft-ietf-httpbis-proxy-status-04.txt >
	HTTP M. Nottingham		HTTP M. Nottingham
	Internet-Draft Fastly		Internet-Draft Fastly
	Intended status: Standards Track P. Sikora		Intended status: Standards Track P. Sikora
	Expires: 13 August 2021 Google		Expires: 13 August 2021 Google
	9 February 2021		9 February 2021
	The Proxy-Status HTTP Response Header Field		The Proxy-Status HTTP Response Header Field
	draft-ietf-httpbis-proxy-status-03		draft-ietf-httpbis-proxy-status-04
	Abstract		Abstract
	This document defines the Proxy-Status HTTP field to convey the		This document defines the Proxy-Status HTTP field to convey the
	details of intermediary response handling, including generated		details of intermediary response handling, including generated
	errors.		errors.
	Note to Readers		Note to Readers
	_RFC EDITOR: please remove this section before publication_		_RFC EDITOR: please remove this section before publication_
	skipping to change at page 2, line 28 ¶		skipping to change at page 2, line 28 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4		1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
	2. The Proxy-Status HTTP Field . . . . . . . . . . . . . . . . . 4		2. The Proxy-Status HTTP Field . . . . . . . . . . . . . . . . . 4
	2.1. Proxy-Status Parameters . . . . . . . . . . . . . . . . . 5		2.1. Proxy-Status Parameters . . . . . . . . . . . . . . . . . 5
	2.1.1. error . . . . . . . . . . . . . . . . . . . . . . . . 5		2.1.1. error . . . . . . . . . . . . . . . . . . . . . . . . 5
	2.1.2. next-hop . . . . . . . . . . . . . . . . . . . . . . 6		2.1.2. next-hop . . . . . . . . . . . . . . . . . . . . . . 6
	2.1.3. next-protocol . . . . . . . . . . . . . . . . . . . . 7		2.1.3. next-protocol . . . . . . . . . . . . . . . . . . . . 7
	2.2. received-status . . . . . . . . . . . . . . . . . . . . . 7		2.1.4. received-status . . . . . . . . . . . . . . . . . . . 7
	2.2.1. details . . . . . . . . . . . . . . . . . . . . . . . 7		2.1.5. details . . . . . . . . . . . . . . . . . . . . . . . 7
	2.3. Defining New Proxy-Status Parameters . . . . . . . . . . 7		2.2. Defining New Proxy-Status Parameters . . . . . . . . . . 7
	2.4. Proxy Error Types . . . . . . . . . . . . . . . . . . . . 8		2.3. Proxy Error Types . . . . . . . . . . . . . . . . . . . . 8
	2.4.1. DNS Timeout . . . . . . . . . . . . . . . . . . . . . 8		2.3.1. DNS Timeout . . . . . . . . . . . . . . . . . . . . . 8
	2.4.2. DNS Error . . . . . . . . . . . . . . . . . . . . . . 8		2.3.2. DNS Error . . . . . . . . . . . . . . . . . . . . . . 8
	2.4.3. Destination Not Found . . . . . . . . . . . . . . . . 9		2.3.3. Destination Not Found . . . . . . . . . . . . . . . . 9
	2.4.4. Destination Unavailable . . . . . . . . . . . . . . . 9		2.3.4. Destination Unavailable . . . . . . . . . . . . . . . 9
	2.4.5. Destination IP Prohibited . . . . . . . . . . . . . . 9		2.3.5. Destination IP Prohibited . . . . . . . . . . . . . . 9
	2.4.6. Destination IP Unroutable . . . . . . . . . . . . . . 10		2.3.6. Destination IP Unroutable . . . . . . . . . . . . . . 10
	2.4.7. Connection Refused . . . . . . . . . . . . . . . . . 10		2.3.7. Connection Refused . . . . . . . . . . . . . . . . . 10
	2.4.8. Connection Terminated . . . . . . . . . . . . . . . . 10		2.3.8. Connection Terminated . . . . . . . . . . . . . . . . 10
	2.4.9. Connection Timeout . . . . . . . . . . . . . . . . . 10		2.3.9. Connection Timeout . . . . . . . . . . . . . . . . . 10
	2.4.10. Connection Read Timeout . . . . . . . . . . . . . . . 11		2.3.10. Connection Read Timeout . . . . . . . . . . . . . . . 11
	2.4.11. Connection Write Timeout . . . . . . . . . . . . . . 11		2.3.11. Connection Write Timeout . . . . . . . . . . . . . . 11
	2.4.12. Connection Limit Reached . . . . . . . . . . . . . . 11		2.3.12. Connection Limit Reached . . . . . . . . . . . . . . 11
	2.4.13. TLS Protocol Error . . . . . . . . . . . . . . . . . 11		2.3.13. TLS Protocol Error . . . . . . . . . . . . . . . . . 11
	2.4.14. TLS Certificate Error . . . . . . . . . . . . . . . . 12		2.3.14. TLS Certificate Error . . . . . . . . . . . . . . . . 12
	2.4.15. TLS Alert Received . . . . . . . . . . . . . . . . . 12		2.3.15. TLS Alert Received . . . . . . . . . . . . . . . . . 12
	2.4.16. HTTP Request Error . . . . . . . . . . . . . . . . . 13		2.3.16. HTTP Request Error . . . . . . . . . . . . . . . . . 13
	2.4.17. HTTP Request Denied . . . . . . . . . . . . . . . . . 13		2.3.17. HTTP Request Denied . . . . . . . . . . . . . . . . . 13
	2.4.18. HTTP Incomplete Response . . . . . . . . . . . . . . 13		2.3.18. HTTP Incomplete Response . . . . . . . . . . . . . . 13
	2.4.19. HTTP Response Header Section Too Large . . . . . . . 14		2.3.19. HTTP Response Header Section Too Large . . . . . . . 14
	2.4.20. HTTP Response Header Too Large . . . . . . . . . . . 14		2.3.20. HTTP Response Header Too Large . . . . . . . . . . . 14
	2.4.21. HTTP Response Body Too Large . . . . . . . . . . . . 14		2.3.21. HTTP Response Body Too Large . . . . . . . . . . . . 14
	2.4.22. HTTP Response Trailer Section Too Large . . . . . . . 15		2.3.22. HTTP Response Trailer Section Too Large . . . . . . . 15
	2.4.23. HTTP Response Trailer Too Large . . . . . . . . . . . 15		2.3.23. HTTP Response Trailer Too Large . . . . . . . . . . . 15
	2.4.24. HTTP Response Transfer-Coding Error . . . . . . . . . 16		2.3.24. HTTP Response Transfer-Coding Error . . . . . . . . . 16
	2.4.25. HTTP Response Content-Coding Error . . . . . . . . . 16		2.3.25. HTTP Response Content-Coding Error . . . . . . . . . 16
	2.4.26. HTTP Response Timeout . . . . . . . . . . . . . . . . 16		2.3.26. HTTP Response Timeout . . . . . . . . . . . . . . . . 16
	2.4.27. HTTP Upgrade Failed . . . . . . . . . . . . . . . . . 17		2.3.27. HTTP Upgrade Failed . . . . . . . . . . . . . . . . . 17
	2.4.28. HTTP Protocol Error . . . . . . . . . . . . . . . . . 17		2.3.28. HTTP Protocol Error . . . . . . . . . . . . . . . . . 17
	2.4.29. Proxy Internal Response . . . . . . . . . . . . . . . 17		2.3.29. Proxy Internal Response . . . . . . . . . . . . . . . 17
	2.4.30. Proxy Internal Error . . . . . . . . . . . . . . . . 17		2.3.30. Proxy Internal Error . . . . . . . . . . . . . . . . 17
	2.4.31. Proxy Configuration Error . . . . . . . . . . . . . . 18		2.3.31. Proxy Configuration Error . . . . . . . . . . . . . . 18
	2.4.32. Proxy Loop Detected . . . . . . . . . . . . . . . . . 18		2.3.32. Proxy Loop Detected . . . . . . . . . . . . . . . . . 18
	2.5. Defining New Proxy Error Types . . . . . . . . . . . . . 18		2.4. Defining New Proxy Error Types . . . . . . . . . . . . . 18
	3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19		3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 19		4. Security Considerations . . . . . . . . . . . . . . . . . . . 19
	5. References . . . . . . . . . . . . . . . . . . . . . . . . . 20		5. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
	5.1. Normative References . . . . . . . . . . . . . . . . . . 20		5.1. Normative References . . . . . . . . . . . . . . . . . . 20
	5.2. Informative References . . . . . . . . . . . . . . . . . 20		5.2. Informative References . . . . . . . . . . . . . . . . . 20
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
	1. Introduction		1. Introduction
	HTTP intermediaries -- including both forward proxies and gateways		HTTP intermediaries -- including both forward proxies and gateways
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	example, 502 Bad Gateway and 504 Gateway Timeout. However,		example, 502 Bad Gateway and 504 Gateway Timeout. However,
	experience has shown that more information is necessary to aid		experience has shown that more information is necessary to aid
	debugging and communicate what's happened to the client.		debugging and communicate what's happened to the client.
	Additionally, intermediaries sometimes want to convey additional		Additionally, intermediaries sometimes want to convey additional
	information about their handling of a response, even if they did not		information about their handling of a response, even if they did not
	generate it.		generate it.
	To enable these uses, Section 2 defines a new HTTP response field to		To enable these uses, Section 2 defines a new HTTP response field to
	allow intermediaries to convey details of their handling of a		allow intermediaries to convey details of their handling of a
	response, Section 2.1 enumerates the kind of information that can be		response, Section 2.1 enumerates the kind of information that can be
	conveyed, and Section 2.4 defines a set of error types for use when a		conveyed, and Section 2.3 defines a set of error types for use when a
	proxy encounters an issue when obtaining a response for the request.		proxy encounters an issue when obtaining a response for the request.
	1.1. Notational Conventions		1.1. Notational Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
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	The "error" parameter's value is an sf-token that is a Proxy Error		The "error" parameter's value is an sf-token that is a Proxy Error
	Type. When present, it indicates that the proxy encountered an issue		Type. When present, it indicates that the proxy encountered an issue
	when obtaining a response.		when obtaining a response.
	Unless a Proxy Error Type specifies otherwise, the presences of error		Unless a Proxy Error Type specifies otherwise, the presences of error
	often, but not always, indicates that response was generated by the		often, but not always, indicates that response was generated by the
	proxy, not the origin server or any other upstream server. For		proxy, not the origin server or any other upstream server. For
	example, a proxy might attempt to correct an error, or part of a		example, a proxy might attempt to correct an error, or part of a
	response might be forwarded before the error is encountered.		response might be forwarded before the error is encountered.
	Section 2.4 lists the Proxy Error Types defined in this document; new		Section 2.3 lists the Proxy Error Types defined in this document; new
	ones can be defined using the procedure outlined in Section 2.5.		ones can be defined using the procedure outlined in Section 2.4.
	For example:		For example:
	HTTP/1.1 504 Gateway Timeout		HTTP/1.1 504 Gateway Timeout
	Proxy-Status: SomeCDN; error=connection_timeout		Proxy-Status: SomeCDN; error=connection_timeout
	indicates that this 504 response was generated by SomeCDN, due to a		indicates that this 504 response was generated by SomeCDN, due to a
	connection timeout when going forward.		connection timeout when going forward.
	Or:		Or:
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	Proxy-Status: SomeReverseProxy; error=http_request_error		Proxy-Status: SomeReverseProxy; error=http_request_error
	indicates that this 429 Too Many Requests response was generated by		indicates that this 429 Too Many Requests response was generated by
	the intermediary, not the origin.		the intermediary, not the origin.
	When sending the error parameter, the most specific Proxy Error Type		When sending the error parameter, the most specific Proxy Error Type
	SHOULD be sent, provided that it accurately represents the error		SHOULD be sent, provided that it accurately represents the error
	condition. If an appropriate Proxy Error Type is not defined, there		condition. If an appropriate Proxy Error Type is not defined, there
	are a number of generic error types (e.g., proxy_internal_error,		are a number of generic error types (e.g., proxy_internal_error,
	http_protocol_error) that can be used. If they are not suitable,		http_protocol_error) that can be used. If they are not suitable,
	consider registering a new Proxy Error Type (see Section 2.5).		consider registering a new Proxy Error Type (see Section 2.4).
	Each Proxy Error Type has a Recommended HTTP Status Code. When		Each Proxy Error Type has a Recommended HTTP Status Code. When
	generating a HTTP response containing "error", its HTTP status code		generating a HTTP response containing "error", its HTTP status code
	SHOULD be set to the Recommended HTTP Status Code. However, there		SHOULD be set to the Recommended HTTP Status Code. However, there
	may be circumstances (e.g., for backwards compatibility with previous		may be circumstances (e.g., for backwards compatibility with previous
	behaviours, a status code has already been sent) when another status		behaviours, a status code has already been sent) when another status
	code might be used.		code might be used.
	Proxy Error Types can also define any number of extra parameters for		Proxy Error Types can also define any number of extra parameters for
	use with that type. Their use, like all parameters, is optional. As		use with that type. Their use, like all parameters, is optional. As
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	established.		established.
	The value MUST be either an sf-token or sf-binary. If the protocol		The value MUST be either an sf-token or sf-binary. If the protocol
	identifier is able to be expressed as an sf-token using UTF-8		identifier is able to be expressed as an sf-token using UTF-8
	encoding, that form MUST be used.		encoding, that form MUST be used.
	For example:		For example:
	Proxy-Status: "proxy.example.org"; next-protocol=h2		Proxy-Status: "proxy.example.org"; next-protocol=h2
	2.2. received-status		2.1.4. received-status
	The "received-status" parameter's value indicates the HTTP status		The "received-status" parameter's value indicates the HTTP status
	code that the intermediary received from the next hop server.		code that the intermediary received from the next hop server.
	The value MUST be an sf-integer.		The value MUST be an sf-integer.
	For example:		For example:
	Proxy-Status: ExampleProxy; received-status=200		Proxy-Status: ExampleProxy; received-status=200
	2.2.1. details		2.1.5. details
	The "details" parameter's value is an sf-string containing additional		The "details" parameter's value is an sf-string containing additional
	information not captured anywhere else. This can include		information not captured anywhere else. This can include
	implementation-specific or deployment-specific information.		implementation-specific or deployment-specific information.
	For example:		For example:
	Proxy-Status: ExampleProxy; error="http_protocol_error";		Proxy-Status: ExampleProxy; error="http_protocol_error";
	details="Malformed response header - space before colon"		details="Malformed response header - space before colon"
	2.3. Defining New Proxy-Status Parameters		2.2. Defining New Proxy-Status Parameters
	New Proxy-Status Parameters can be defined by registering them in the		New Proxy-Status Parameters can be defined by registering them in the
	HTTP Proxy-Status Parameters registry.		HTTP Proxy-Status Parameters registry.
	Registration requests are reviewed and approved by a Designated		Registration requests are reviewed and approved by a Designated
	Expert, as per [RFC8126], Section 4.5. A specification document is		Expert, as per [RFC8126], Section 4.5. A specification document is
	appreciated, but not required.		appreciated, but not required.
	The Expert(s) should consider the following factors when evaluating		The Expert(s) should consider the following factors when evaluating
	requests:		requests:
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	* Name: [a name for the Proxy-Status Parameter that matches key]		* Name: [a name for the Proxy-Status Parameter that matches key]
	* Description: [a description of the parameter semantics and value]		* Description: [a description of the parameter semantics and value]
	* Reference: [to a specification defining this parameter]		* Reference: [to a specification defining this parameter]
	See the registry at https://iana.org/assignments/http-proxy-status		See the registry at https://iana.org/assignments/http-proxy-status
	(https://iana.org/assignments/http-proxy-status) for details on where		(https://iana.org/assignments/http-proxy-status) for details on where
	to send registration requests.		to send registration requests.
	2.4. Proxy Error Types		2.3. Proxy Error Types
	This section lists the Proxy Error Types defined by this document.		This section lists the Proxy Error Types defined by this document.
	See Section 2.5 for information about defining new Proxy Error Types.		See Section 2.4 for information about defining new Proxy Error Types.
	2.4.1. DNS Timeout		2.3.1. DNS Timeout
	* Name: dns_timeout		* Name: dns_timeout
	* Description: The intermediary encountered a timeout when trying to		* Description: The intermediary encountered a timeout when trying to
	find an IP address for the next hop hostname.		find an IP address for the next hop hostname.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
	2.4.2. DNS Error		2.3.2. DNS Error
	* Name: dns_error		* Name: dns_error
	* Description: The intermediary encountered a DNS error when trying		* Description: The intermediary encountered a DNS error when trying
	to find an IP address for the next hop hostname.		to find an IP address for the next hop hostname.
	* Extra Parameters:		* Extra Parameters:
	- rcode: A sf-string conveying the DNS RCODE that indicates the		- rcode: A sf-string conveying the DNS RCODE that indicates the
	error type. See [RFC8499], Section 3.		error type. See [RFC8499], Section 3.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	2.4.3. Destination Not Found		2.3.3. Destination Not Found
	* Name: destination_not_found		* Name: destination_not_found
	* Description: The intermediary cannot determine the appropriate		* Description: The intermediary cannot determine the appropriate
	next hop to use for this request; for example, it may not be		next hop to use for this request; for example, it may not be
	configured. Note that this error is specific to gateways, which		configured. Note that this error is specific to gateways, which
	typically require specific configuration to identify the "backend"		typically require specific configuration to identify the "backend"
	server; forward proxies use in-band information to identify the		server; forward proxies use in-band information to identify the
	origin server.		origin server.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 500		* Recommended HTTP status code: 500
	2.4.4. Destination Unavailable		2.3.4. Destination Unavailable
	* Name: destination_unavailable		* Name: destination_unavailable
	* Description: The intermediary considers the next hop to be		* Description: The intermediary considers the next hop to be
	unavailable; e.g., recent attempts to communicate with it may have		unavailable; e.g., recent attempts to communicate with it may have
	failed, or a health check may indicate that it is down.		failed, or a health check may indicate that it is down.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 503		* Recommended HTTP status code: 503
	2.4.5. Destination IP Prohibited		2.3.5. Destination IP Prohibited
	* Name: destination_ip_prohibited		* Name: destination_ip_prohibited
	* Description: The intermediary is configured to prohibit		* Description: The intermediary is configured to prohibit
	connections to the next hop IP address.		connections to the next hop IP address.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	2.4.6. Destination IP Unroutable		2.3.6. Destination IP Unroutable
	* Name: destination_ip_unroutable		* Name: destination_ip_unroutable
	* Description: The intermediary cannot find a route to the next hop		* Description: The intermediary cannot find a route to the next hop
	IP address.		IP address.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	2.4.7. Connection Refused		2.3.7. Connection Refused
	* Name: connection_refused		* Name: connection_refused
	* Description: The intermediary's connection to the next hop was		* Description: The intermediary's connection to the next hop was
	refused.		refused.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	2.4.8. Connection Terminated		2.3.8. Connection Terminated
	* Name: connection_terminated		* Name: connection_terminated
	* Description: The intermediary's connection to the next hop was		* Description: The intermediary's connection to the next hop was
	closed before complete response was received.		closed before complete response was received.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.9. Connection Timeout		2.3.9. Connection Timeout
	* Name: connection_timeout		* Name: connection_timeout
	* Description: The intermediary's attempt to open a connection to		* Description: The intermediary's attempt to open a connection to
	the next hop timed out.		the next hop timed out.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
	2.4.10. Connection Read Timeout		2.3.10. Connection Read Timeout
	* Name: connection_read_timeout		* Name: connection_read_timeout
	* Description: The intermediary was expecting data on a connection		* Description: The intermediary was expecting data on a connection
	(e.g., part of a response), but did not receive any new data in a		(e.g., part of a response), but did not receive any new data in a
	configured time limit.		configured time limit.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.11. Connection Write Timeout		2.3.11. Connection Write Timeout
	* Name: connection_write_timeout		* Name: connection_write_timeout
	* Description: The intermediary was attempting to write data to a		* Description: The intermediary was attempting to write data to a
	connection, but was not able to (e.g., because its buffers were		connection, but was not able to (e.g., because its buffers were
	full).		full).
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.12. Connection Limit Reached		2.3.12. Connection Limit Reached
	* Name: connection_limit_reached		* Name: connection_limit_reached
	* Description: The intermediary is configured to limit the number of		* Description: The intermediary is configured to limit the number of
	connections it has to the next hop, and that limit has been		connections it has to the next hop, and that limit has been
	passed.		passed.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 503		* Recommended HTTP status code: 503
	2.4.13. TLS Protocol Error		2.3.13. TLS Protocol Error
	* Name: tls_protocol_error		* Name: tls_protocol_error
	* Description: The intermediary encountered a TLS error when		* Description: The intermediary encountered a TLS error when
	communicating with the next hop, either during handshake or		communicating with the next hop, either during handshake or
	afterwards.		afterwards.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.4.14. TLS Certificate Error		2.3.14. TLS Certificate Error
	* Name: tls_certificate_error		* Name: tls_certificate_error
	* Description: The intermediary encountered an error when verifying		* Description: The intermediary encountered an error when verifying
	the certificate presented by the next hop.		the certificate presented by the next hop.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.4.15. TLS Alert Received		2.3.15. TLS Alert Received
	* Name: tls_alert_received		* Name: tls_alert_received
	* Description: The intermediary received a TLS alert from the next		* Description: The intermediary received a TLS alert from the next
	hop.		hop.
	* Extra Parameters:		* Extra Parameters:
	- alert-message: an sf-token containing the applicable		- alert-message: an sf-token containing the applicable
	description string from the TLS Alerts registry.		description string from the TLS Alerts registry.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.16. HTTP Request Error		2.3.16. HTTP Request Error
	* Name: http_request_error		* Name: http_request_error
	* Description: The intermediary is generating a client (4xx)		* Description: The intermediary is generating a client (4xx)
	response on the origin's behalf. Applicable status codes include		response on the origin's behalf. Applicable status codes include
	(but are not limited to) 400, 403, 405, 406, 408, 411, 413, 414,		(but are not limited to) 400, 403, 405, 406, 408, 411, 413, 414,
	415, 416, 417, 429.		415, 416, 417, 429.
	* Extra Parameters:		* Extra Parameters:
	skipping to change at page 13, line 27 ¶		skipping to change at page 13, line 27 ¶
	code.		code.
	- status-phrase: an sf-string containing the generated status		- status-phrase: an sf-string containing the generated status
	phrase.		phrase.
	* Recommended HTTP status code: The applicable 4xx status code		* Recommended HTTP status code: The applicable 4xx status code
	* Notes: This type helps distinguish between responses generated by		* Notes: This type helps distinguish between responses generated by
	intermediaries from those generated by the origin.		intermediaries from those generated by the origin.
	2.4.17. HTTP Request Denied		2.3.17. HTTP Request Denied
	* Name: http_request_denied		* Name: http_request_denied
	* Description: The intermediary rejected the HTTP request based on		* Description: The intermediary rejected the HTTP request based on
	its configuration and/or policy settings. The request wasn't		its configuration and/or policy settings. The request wasn't
	forwarded to the next hop.		forwarded to the next hop.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 403		* Recommended HTTP status code: 403
	2.4.18. HTTP Incomplete Response		2.3.18. HTTP Incomplete Response
	* Name: http_response_incomplete		* Name: http_response_incomplete
	* Description: The intermediary received an incomplete response to		* Description: The intermediary received an incomplete response to
	the request from the next hop.		the request from the next hop.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.19. HTTP Response Header Section Too Large		2.3.19. HTTP Response Header Section Too Large
	* Name: http_response_header_section_size		* Name: http_response_header_section_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	whose header section was considered too large.		whose header section was considered too large.
	* Extra Parameters:		* Extra Parameters:
	- header-section-size: an sf-integer indicating how large the		- header-section-size: an sf-integer indicating how large the
	headers received were. Note that they might not be complete;		headers received were. Note that they might not be complete;
	i.e., the intermediary may have discarded or refused additional		i.e., the intermediary may have discarded or refused additional
	data.		data.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.20. HTTP Response Header Too Large		2.3.20. HTTP Response Header Too Large
	* Name: http_response_header_size		* Name: http_response_header_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	containing an individual header line that was considered too		containing an individual header line that was considered too
	large.		large.
	* Extra Parameters:		* Extra Parameters:
	- header-name: an sf-string indicating the name of the header		- header-name: an sf-string indicating the name of the header
	that triggered the error.		that triggered the error.
	- header-size: an sf-integer indicating the size of the header		- header-size: an sf-integer indicating the size of the header
	that triggered the error.		that triggered the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.21. HTTP Response Body Too Large		2.3.21. HTTP Response Body Too Large
	* Name: http_response_body_size		* Name: http_response_body_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	whose body was considered too large.		whose body was considered too large.
	* Extra Parameters:		* Extra Parameters:
	- body-size: an sf-integer indicating how large the body received		- body-size: an sf-integer indicating how large the body received
	was. Note that it may not have been complete; i.e., the		was. Note that it may not have been complete; i.e., the
	intermediary may have discarded or refused additional data.		intermediary may have discarded or refused additional data.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.22. HTTP Response Trailer Section Too Large		2.3.22. HTTP Response Trailer Section Too Large
	* Name: http_response_trailer_section_size		* Name: http_response_trailer_section_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	whose trailer section was considered too large.		whose trailer section was considered too large.
	* Extra Parameters:		* Extra Parameters:
	- trailer-section-size: an sf-integer indicating how large the		- trailer-section-size: an sf-integer indicating how large the
	trailers received were. Note that they might not be complete;		trailers received were. Note that they might not be complete;
	i.e., the intermediary may have discarded or refused additional		i.e., the intermediary may have discarded or refused additional
	data.		data.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.23. HTTP Response Trailer Too Large		2.3.23. HTTP Response Trailer Too Large
	* Name: http_response_trailer_size		* Name: http_response_trailer_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	containing an individual trailer line that was considered too		containing an individual trailer line that was considered too
	large.		large.
	* Extra Parameters:		* Extra Parameters:
	- trailer-name: an sf-string indicating the name of the trailer		- trailer-name: an sf-string indicating the name of the trailer
	that triggered the error.		that triggered the error.
	- trailer-size: an sf-integer indicating the size of the trailer		- trailer-size: an sf-integer indicating the size of the trailer
	that triggered the error.		that triggered the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.24. HTTP Response Transfer-Coding Error		2.3.24. HTTP Response Transfer-Coding Error
	* Name: http_response_transfer_coding		* Name: http_response_transfer_coding
	* Description: The intermediary encountered an error decoding the		* Description: The intermediary encountered an error decoding the
	transfer-coding of the response.		transfer-coding of the response.
	* Extra Parameters:		* Extra Parameters:
	- coding: an sf-token containing the specific coding that caused		- coding: an sf-token containing the specific coding that caused
	the error.		the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.25. HTTP Response Content-Coding Error		2.3.25. HTTP Response Content-Coding Error
	* Name: http_response_content_coding		* Name: http_response_content_coding
	* Description: The intermediary encountered an error decoding the		* Description: The intermediary encountered an error decoding the
	content-coding of the response.		content-coding of the response.
	* Extra Parameters:		* Extra Parameters:
	- coding: an sf-token containing the specific coding that caused		- coding: an sf-token containing the specific coding that caused
	the error.		the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.26. HTTP Response Timeout		2.3.26. HTTP Response Timeout
	* Name: http_response_timeout		* Name: http_response_timeout
	* Description: The intermediary reached a configured time limit		* Description: The intermediary reached a configured time limit
	waiting for the complete response.		waiting for the complete response.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.4.27. HTTP Upgrade Failed		2.3.27. HTTP Upgrade Failed
	* Name: http_upgrade_failed		* Name: http_upgrade_failed
	* Description: The HTTP Upgrade between the intermediary and the		* Description: The HTTP Upgrade between the intermediary and the
	next hop failed.		next hop failed.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	2.4.28. HTTP Protocol Error		2.3.28. HTTP Protocol Error
	* Name: http_protocol_error		* Name: http_protocol_error
	* Description: The intermediary encountered a HTTP protocol error		* Description: The intermediary encountered a HTTP protocol error
	when communicating with the next hop. This error should only be		when communicating with the next hop. This error should only be
	used when a more specific one is not defined.		used when a more specific one is not defined.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.4.29. Proxy Internal Response		2.3.29. Proxy Internal Response
	* Name: proxy_internal_response		* Name: proxy_internal_response
	* Description: The intermediary generated the response locally,		* Description: The intermediary generated the response locally,
	without attempting to connect to the next hop (e.g. in response to		without attempting to connect to the next hop (e.g. in response to
	a request to a debug endpoint terminated at the intermediary).		a request to a debug endpoint terminated at the intermediary).
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code:		* Recommended HTTP status code:
	2.4.30. Proxy Internal Error		2.3.30. Proxy Internal Error
	* Name: proxy_internal_error		* Name: proxy_internal_error
	* Description: The intermediary encountered an internal error		* Description: The intermediary encountered an internal error
	unrelated to the origin.		unrelated to the origin.
	* Extra Parameters: None		* Extra Parameters: None
	* Recommended HTTP status code: 500		* Recommended HTTP status code: 500
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.4.31. Proxy Configuration Error		2.3.31. Proxy Configuration Error
	* Name: proxy_configuration_error		* Name: proxy_configuration_error
	* Description: The intermediary encountered an error regarding its		* Description: The intermediary encountered an error regarding its
	configuration.		configuration.
	* Extra Parameters: None		* Extra Parameters: None
	* Recommended HTTP status code: 500		* Recommended HTTP status code: 500
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.4.32. Proxy Loop Detected		2.3.32. Proxy Loop Detected
	* Name: proxy_loop_detected		* Name: proxy_loop_detected
	* Description: The intermediary tried to forward the request to		* Description: The intermediary tried to forward the request to
	itself, or a loop has been detected using different means (e.g.		itself, or a loop has been detected using different means (e.g.
	[RFC8586]).		[RFC8586]).
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
	2.5. Defining New Proxy Error Types		2.4. Defining New Proxy Error Types
	New Proxy Error Types can be defined by registering them in the HTTP		New Proxy Error Types can be defined by registering them in the HTTP
	Proxy Error Types registry.		Proxy Error Types registry.
	Registration requests are reviewed and approved by a Designated		Registration requests are reviewed and approved by a Designated
	Expert, as per [RFC8126], Section 4.5. A specification document is		Expert, as per [RFC8126], Section 4.5. A specification document is
	appreciated, but not required.		appreciated, but not required.
	The Expert(s) should consider the following factors when evaluating		The Expert(s) should consider the following factors when evaluating
	requests:		requests:
	skipping to change at page 19, line 43 ¶		skipping to change at page 19, line 43 ¶
	See the registry at https://iana.org/assignments/http-proxy-status		See the registry at https://iana.org/assignments/http-proxy-status
	(https://iana.org/assignments/http-proxy-status) for details on where		(https://iana.org/assignments/http-proxy-status) for details on where
	to send registration requests.		to send registration requests.
	3. IANA Considerations		3. IANA Considerations
	Upon publication, please create the HTTP Proxy-Status Parameters		Upon publication, please create the HTTP Proxy-Status Parameters
	registry and the HTTP Proxy Error Types registry at		registry and the HTTP Proxy Error Types registry at
	https://iana.org/assignments/http-proxy-statuses		https://iana.org/assignments/http-proxy-statuses
	(https://iana.org/assignments/http-proxy-statuses) and populate them		(https://iana.org/assignments/http-proxy-statuses) and populate them
	with the types defined in Section 2.1 and Section 2.4 respectively;		with the types defined in Section 2.1 and Section 2.3 respectively;
	see Section 2.3 and Section 2.5 for its associated procedures.		see Section 2.2 and Section 2.4 for its associated procedures.
	4. Security Considerations		4. Security Considerations
	One of the primary security concerns when using Proxy-Status is		One of the primary security concerns when using Proxy-Status is
	leaking information that might aid an attacker. For example,		leaking information that might aid an attacker. For example,
	information about the intermediary's configuration and back-end		information about the intermediary's configuration and back-end
	topology can be exposed.		topology can be exposed.
	As a result, care needs to be taken when deciding to generate a		As a result, care needs to be taken when deciding to generate a
	Proxy-Status field. Note that intermediaries are not required to		Proxy-Status field. Note that intermediaries are not required to
End of changes. 44 change blocks.
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